That reminds me of a conversation I had nearly a decade ago with a black (African immigrant) friend. I don't remember the details, but basically he said that he was annoyed that the words "dark" and "black" had negative connotations. I knew him well enough to know that he wasn't trolling, and that this was something that had seriously taken an emotional toll on him.
Ever since then I've been thinking about this -- maybe it does bother a lot of black folks? And, think of very little whose conception of words is primitive, and how they might associate the words together.
I don't really know what I'm getting it. It's very hard to make any sort of conclusion here. I mean, what's the cure -- we make a prescriptive linguistic change that color-based words can't be used anymore? That's not happening.
The concept of dark/black being scary I'm confident pre-dates any racism towards african americans.
Also, there are a few things where black is used as positive.
- Finance; If you're "in the black", you're flushed with cash. There's some kinda dark irony here. ;)
- Rich people tend to wear expensive black clothes, expensive black cars... etc. Black is always in fashion and a symbol of wealth... which somehow, again, is ironic. ;)
The black finance thing is rather simple - in bookkeeping, a positive total is written in normal ink, which is (usually) black. A negative total is written in red ink, to make it stand out. Being in the black just means you're not making a loss, though when used colloquially, as you say, it means you are flush with cash.
Red is the color of life, of hearty blush in skin.
The verse starts: "Black cat is bad luck, bad guys wear black. Musta been a white guy who started all that."
Interestingly, the MC in question here is white-skinned. I think he's Jewish, but I might be wrong.
From the perspective of an African immigrant, I would imagine that it is easy to see discrimination everywhere. I think your friend is annoyed that the idea of "blackness being inferior" is omnipresent (from his perspective). It's even built in to the very way we speak.
I think that what your immigrant friend really wants is just to feel like he has the same shot a person with white skin does. He's kvetching about words because racism is on his mind a lot, but he's not expecting you or anyone to rewrite the English language. He probably just gets treated poorly on a regular basis because of his race, and he wants that to stop.
You (We) could likely cure his annoyances while stopping short of major linguistic changes.
Sometimes people are actively looking to be offended. Take this one for example: https://www.youtube.com/watch?v=oc1zGRUPztc